Cardiac magnetic resonance imaging (MRI) provides a non-invasive way to evaluate the morphology and function of the heart from the imaging data. Specifically, dynamic cine imaging, which generates a 2D image sequence to cover a full cardiac cycle, can provide direct information of heart motion.
Due to the long imaging time and breath-holding requirements, the clinical cardiac MRI imaging protocols are still 2D sequences.
To recover the 3D motion field of the whole heart wall, typically we need to scan several slices in long axis (2-, 3-, 4-chamber) views and short-axis (SAX) views, as shown in Fig. REF . There are two kinds of dynamic imaging: conventional (untagged) cine MR imaging and tagging imaging (t-MRI) [1]}.
For untagged cine images (most recent work has focused on these images), feature tracking can be used to estimate myocardial motion [2]}, [3]}, [4]}, [5]}, [6]}, [7]}.
However, as shown in Fig. REF  (b), due to the relatively uniform signal in the myocardial wall and the lack of reliable identifiable landmarks, the estimated motion cannot be used as a reliable indicator for clinical diagnosis.
In contrast, t-MRI provides the gold standard imaging method for regional myocardial motion quantification and strain estimation.
The t-MRI data is produced by a specially designed magnetic preparation module called spatial modulation of magnetization (SPAMM) [8]}. It introduces the intrinsic tissue markers which are stripe-like darker tag patterns embedded in relatively brighter myocardium, as shown in Fig. REF  (a). By tracking the deformation of tags, we can retrieve a 2D displacement field in the imaging plane and recover magnetization, which non-invasively creates fiducial “tags" within the heart wall.
